Method and apparatus for mission critical standby of a portable communication drive

ABSTRACT

A method and apparatus for mission critical standby of a portable communication device are disclosed. A portable communication device may include a primary processor for a first operating platform, a secondary processor for a second operating platform and communicatively coupled to the primary processor, and a power state manager that may have a first mode and a second mode. The power state manager may be configured to determine whether the primary processor is in a powered off state and sequence supply of power to the secondary processor. The first mode may allow the primary processor to monitor a power state of the secondary processor based on a determination that the primary processor is not in the powered off state and the second mode may enable the power state manager to monitor the power state based on a determination that the primary processor is in the powered off state.

BACKGROUND OF THE INVENTION

Many portable communication devices, such as two-way radios, areutilized to perform different types of communication. These types ofcommunication, which may occur separately or in parallel, includestanding wave radio transmission, land mobile radio (LMR) transmission,and long-term evolution (LTE) transmission. Portable communicationdevices may be battery-powered and may include multiple components,including a transceiver and one or more processors, for mission criticaloperations.

Without power management, one or more components of the portablecommunication may remain in an active state, draw excessive power, andcause excessive discharge of the battery. One or more processors inpresent portable communication devices may manage the power of thecomponents when powered on. However, there are situations in which itmay not be feasible for the processors to manage power consumption whenpowered off. When one or more processors are turned off, presentportable communication devices do not control excessive discharge of thebattery.

There exists a limitation with respect to managing the discharge of thebattery when one or more processors of the portable communicationdevices for mission critical operations are turned off. Thisfunctionality typically may not be achieved by simply keeping theprocessors powered on.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The accompanying figures, where like reference numerals refer toidentical or functionally similar elements throughout the separateviews, together with the detailed description below, are incorporated inand form part of the specification, and serve to further illustrateembodiments of concepts that include the claimed invention, and explainvarious principles and advantages of those embodiments.

FIG. 1 is a perspective view of an example portable communicationdevice, in accordance with some embodiments.

FIG. 2 is a block diagram illustrating an example portable communicationdevice supporting mission critical standby, in accordance with someembodiments.

FIG. 3A is a state diagram illustrating entry and exit from missioncritical standby, in accordance with some embodiments.

FIG. 3B is a state diagram illustrating mission critical standby, inaccordance with some embodiments.

FIG. 4A is a flowchart illustrating a method for mission criticalstandby on a portable communication device, in accordance with someembodiments.

FIG. 4B is a flowchart illustrating a method for mission criticalstandby and cleanup operation on a portable communication device, inaccordance with some embodiments.

Skilled artisans will appreciate that elements in the figures areillustrated for simplicity and clarity and have not necessarily beendrawn to scale. For example, the dimensions of some of the elements inthe figures may be exaggerated relative to other elements to help toimprove understanding of embodiments of the present invention.

The system, method, and apparatus components have been represented whereappropriate by suitable symbols in the drawings, showing only thosespecific details that are pertinent to understanding the embodiments ofthe present invention so as not to obscure the disclosure with detailsthat will be readily apparent to those of ordinary skill in the arthaving the benefit of the description herein.

DETAILED DESCRIPTION OF THE INVENTION

Disclosed herein are systems, methods, and apparatuses for missioncritical standby of a portable communication device.

In one embodiment, a disclosed portable communication device includes aprimary processor, secondary processor communicatively coupled to theprimary processor, and a power state manager. The primary processor maybe for a first operating platform and the secondary processor may be fora second operating platform. The power state manager may be configuredto determine whether the primary processor is in a powered off state andsequence supply of power to the secondary processor. The power statemanager may have a first mode and a second mode. The first mode mayallow the primary processor to monitor the power state of the secondaryprocessor based on a determination that the primary processor is not inthe powered off state. The second mode may enable the power statemanager to monitor the power state of the secondary processor based on adetermination that the primary processor is in the powered off state.

In one embodiment, a disclosed method for sequencing power of a portablecommunication device having a primary processor and a secondaryprocessor includes receiving a first command in response to user input,starting a first timer to limit time spent by the secondary processor ina standby mode, sending a second command to the secondary processor toinitiate cleanup operation, determining whether the first timer expired,and sending a third command to the secondary processor to shut down. Theprimary processor may be for a first operating platform and thesecondary processor may be for a second operating platform. The firstcommand may be to shut down the primary processor and the first timermay be started in response to receiving the first command. The cleanupoperation to be initiated by the second command may be completed priorto shut down of the secondary processor. The third command may be sentbased on a determination that the first timer expired, which may bedetermined relative to a first timeout value.

In at least some embodiments of the present disclosure, the systems,methods, and apparatuses as described herein for mission criticalstandby may support a plurality of processors in which at least one ofthe processors is dedicated to processing mission criticalcommunications. Unlike apparatuses that employ one processor with one ormore processing cores for processing communications, the methods andapparatus as described herein may support mission criticalcommunications without reducing battery life by supporting low powermodes for the plurality of processors, including any processor(s) forsupporting mission critical communications, and without the need to waitfor a consumer level operating system to boot on any processor(s) forsupporting mission critical communications.

In at least some embodiments of the present disclosure, the systems,methods, and apparatuses as described herein for mission criticalstandby may permit monitoring of a secondary processor to be performedby a plurality of components. Unlike apparatuses that employ monitoringof a secondary processor by one component, the methods and apparatus asdescribed herein may support mission critical communications by allowinga primary processor to monitor the secondary processor when the primaryprocessor is powered on and by enabling a power state manager to monitorthe secondary processor when the primary processor is powered off.

In at least some embodiments of the present disclosure, the systems,methods, and apparatuses as described herein for mission criticalstandby may supervise unexpected wakeup events by a secondary processor.Unlike apparatuses that employ consumer level operating systems tomanage power states, the methods and apparatus as described herein maysupport mission critical communications by permitting cleanup operationson a secondary processor for a limited period of time before returningthe secondary processor to standby or initiating shutdown of thesecondary processor.

In at least some embodiments of the present disclosure, the systems,methods, and apparatuses as described herein for mission criticalstandby may force a hard shutdown of the secondary processor. Unlikeapparatuses that employ consumer level operating systems to manage powerstates, the methods and apparatus as described herein may supportmission critical communications by forcing a hard shutdown of thesecondary processor when the secondary processor does not properlyexecute one or more shutdown commands.

Referring now to FIG. 1, there is provided a perspective view of anexample portable communication device 100 with support for missioncritical standby in accordance with some embodiments. In variousembodiments, portable communication device 100 may include antenna 105for the transmission and reception of communication signal(s). Antenna105 may communicate using one or more communication standards including,but not limited to, radio communication and wireless communication.Portable communication device 100 may further include battery 135.Battery 135 may be embedded in portable communication device 100 (notshown) or may be removable from portable communication device 100.Battery 135 may be charged via one or more terminals 140. Battery mayprovide power for one or more components of portable communicationdevice 100, including but not limited to communications.

In various embodiments, portable communication device 100 may includeone or more input devices. In some embodiments, a plurality offront-facing buttons 130 may be used to input information to portablecommunication device 100. In various embodiments, one or moremicrophones 120 may be used to receive audio input to portablecommunication device 100. In some embodiments, primary display 125 ofportable communication device 100 may include a touch input interface tocontrol portable communication device 100. In some embodiments, portablecommunication device 100 may include one or more knobs (110 and 115).Knob 110 may be used to adjust communications. For example, knob 110 mayadjust the state of the radio between on and off. As another example,knob 110 may adjust the volume of the audio output from portablecommunication device 100 such that the radio is turned off when knob 110is adjusted beyond a minimum volume setting. Knob 115 may be used toadjust the communication channel used by portable communication device100.

Referring now to FIG. 2, there is provided a block diagram illustratingan example portable communication device 200 supporting mission criticalstandby. Portable communication device 200 may include a primaryprocessor, such as baseband processor (BP) 202, a secondary processor,such as application processor (AP) 204, power management subsystem 216,and rotary control 212. BP 202 may support communications for missioncritical operations, including but not limited to, one or morecommunications over high-powered land mobile radio (LMR), public safetylong-term evolution (PS LTE), and mission critical push-to-talk overlong-term evolution (MSPTT over LTE). A real-time operating system(RTOS) may execute on BP 202 to provide for mission criticalcommunications without indeterminant delays in processing incoming oroutgoing communications. AP 204 may support one or more communications,including but not limited to, geofencing using a global positioningsystem (GPS), broadband and wireless local area networking (e.g.,Wi-Fi), Bluetooth audio, and consumer long-term evolution (LTE). In someembodiments, one or more accessories may be supported by AP 204,including but not limited to, a wireless earpiece, a wired headset, orany suitable accessory communicatively coupled to AP 204. Aconsumer-level operating system (OS) may execute on AP 204 to providefor one or more communications with indeterminant delays in processingincoming or outgoing communications. For example, the consumer-level OSmay be implemented based on Android™. Skilled artisans will appreciatethat, in some embodiments, the consumer-level OS may be implementedbased on open source operating systems, such as Tizen.

Rotary control 212, which may be referred to as a rotary knob, maycontrol the power state of BP 202 and the monitoring of AP 204. Forexample, rotary control 212 may be implemented as knob 110 as describedfor FIG. 1. Rotary control 212 may toggle the radio of portablecommunication device 200 on and off as the control is rotated. Whenrotary control 212 is switched on, BP 202 may be powered on and maymonitor AP 204, and when rotary control 212 is switched off, BP 202 maybe powered off and power management subsystem 216 may monitor AP 204.Rotary control 212 may provide user input via rotary control status 220to power management subsystem 216. Based on rotary control status 220,power management subsystem 216 may provide rotary status 224 to basebandprocessor power management integrated circuit (BP PMIC) 206 and rotarystatus 248 to AP 204. In some embodiments, when rotary control 212 isswitched off, power management subsystem 216 may request AP 204 to shutdown by indicating to AP 204 via rotary status 248 that rotary control212 is switched on. In response to rotary status 224, BP PMIC 206 maycontrol the power state of BP 202 via one or more outputs, including butnot limited to, baseband processor status (BP status) 228 and basebandprocessor reset (BP reset) 218. BP PMIC 206 may provide power to BP 202via baseband processor power supply (BP power supply) 227. In responseto rotary status 248, AP 204 may reset and then restart or rebootsubstantially in parallel with BP 202. For example, when rotary status224 indicates rotary control 212 is set to on, BP PMIC 206 may assert BPreset 218 before BP PMIC 206 is powered down. BP status 228 may indicatethe power state of BP 202 to power management subsystem 216 and powersupply 210. For example, when BP status 228 is asserted, BP 202 may bein the powered-on state and BP power supply 227 may supply power to BP202. When BP status 228 is de-asserted, BP 202 may be in the powered-offstate and BP power supply may not supply power to BP 202. Skilledartisans will appreciate that in some embodiments, BP status 228 mayindicate more than two states, such as a powered-on state, a low-powerstate, and a powered-off state.

When BP 202 is in the powered-on state, BP 202 may monitor AP 204 overbuses and input/output 254, which may be coupled to isolation buffers214. BP 202 may communicate with power management subsystem 216 viaserial control bus 222 to indicate when AP 204 is being monitored by BP202. Serial control bus 222 may be implemented using any suitableprotocol, including but not limited to I²c and serial peripheralinterface (SPI). When BP 202 is powered on, power management subsystem216 may assert isolation buffer enable 252 to enable isolation buffers214 to adjust or buffer the voltage level of a signal from BP 202 beforesending the signal to AP 204 over buses and input/output 250. BP 202 maymonitor AP 204 to determine the power state of AP 204.

When BP 202 is in the powered-off state, power management subsystem 216may monitor AP 204 and determine the power state of AP 204. In someembodiments, power management subsystem 216 may monitor the voltage ofone or more power supplies corresponding to AP 204 to determine thepower state of AP 204. Power management subsystem 216 may receive anindication whether one or more power supplies corresponding to AP 204have been set to memory retention mode via AP power status 232 frompower supply 210. AP power status 232 may provide information indicativeof the supply of power to the memory of AP 204. In some embodiments, APpower status 232 may represent the comparison between a measured corepower supply voltage and a threshold. When the measured core powersupply voltage is above the threshold at which processing may occur, AP204 may be in an active or cleanup state, and when the measured corepower supply voltage is below the threshold, AP 204 may not be capableof operation and may be in a non-active state, such as a standby state.Skilled artisans will appreciate that in some embodiments, powermanagement subsystem 216 may compare application processor (AP) powerstatus 232 that may represent the measured core power supply voltage toa threshold. When the measured core power supply voltage is indicativeof AP 204 being in a non-active state, memory associated with AP 204 maybe placed in a self-refresh state to retain data without sendinginformation to or receiving information from AP 204.

Skilled artisans will appreciate that other forms of monitoring may beimplemented, including but not limited to, monitoring an indication fromapplication processor power management integrated circuit (AP PMIC) 208,monitoring the state of a clock generator for AP 204, or monitoring atimer or waiting on an interrupt corresponding to activity on AP 204.For example, AP 204 may include a watchdog timer that is reset viaapplication processor (AP) tickle 246 each time power managementsubsystem 216 determines that AP 204 is powered on. When the watchdogtimer is not reset, power management subsystem 216 may provide one ormore outputs to initiate shutdown of AP 204. For example, powermanagement subsystem 216 may provide application processor status (APstatus) 238 to AP PMIC 208. AP status 238 may indicate the power stateof AP 204 to AP PMIC 208, which may assert application processor reset(AP reset) 244 to reset or reboot AP 204 after AP 204 is powered on ormay power down AP 204 by removing power supplied to AP 204 viaapplication processor power supply (AP power supply) 229. As anotherexample, power management subsystem 216 may initiate shutdown of AP 204by asserting or pulsing application processor (AP) shutdown 242, whichmay be received by AP PMIC 208 and AP 204. In some embodiments, powermanagement subsystem 216 may have access to the same information aboutAP 204 as BP 202 and may be able to monitor AP 204 without the need tosynchronize information with BP 202.

In FIG. 2, power supply 210 may draw power from a power source. Forexample, the power source may be battery 135 as described for FIG. 1.Power supply 210 may convert energy from the power source. In someembodiments, power supply 210 may include a plurality of components (notshown) to convert energy from the power source. The converted energy maybe provided by power supply 210 to one or more components of portablecommunication device 200, including but not limited to, BP 202, BP PMIC206, power management subsystem 216, AP 204, and AP PMIC 208. Skilledartisans will appreciate that in some embodiments, the energy providedby power supply 210 may include one or more voltage supplies for use byone or more components of portable communication device 200. Powersupply 210 may include logic to process power state information receivedfrom one or more components of portable communication device 200,including but not limited to, BP PMIC 206 and power management subsystem216.

Power supply 210 may receive power state information from one or morecomponents of portable communication device 200, including but notlimited to, main system status 230, BP status 228, and applicationprocessor (AP) power enable 236. Main system status 250 may indicatewhether portable communication device 200 is powered on. Power supply210 may provide subsystem power supply 234 to power management subsystem216 before power management subsystem 216 indicates via main systemstatus 230 that portable communication device 200 is powered on. BPstatus 228 may indicate whether BP 202 is powered on. When BP status 228indicates that BP 202 is powered on, power supply 210 may provide radiopower supply 226 to BP PMIC 206. AP power enable 236 may indicatewhether AP 204 is powered on. In various embodiments, AP 204 may bepowered on by one or more power supplies, such as AP power supply 229.In some embodiments, power supply 210 may provide battery power supply240 to AP PMIC 208, which may provide power to AP 204 via AP powersupply 229 and indicate that AP 204 is powered on via AP power enable236. Skilled artisans will appreciate that power conversion in portablecommunication device 200 may be implemented using a plurality of powersupplies. For example, subsystem power supply 234 may be implemented astwo power supplies, such as 1.8-volt and 3-volt power supplies.

In various embodiments, one or processors, such as BP 202 and AP 204,may include a microprocessor, a microcontroller, a system-on-a-chip, afield-programmable gate array, a programmable mixed-signal array, or, ingeneral, any system or sub-system that includes nominal memory and thatis capable of executing a sequence of instructions to control hardware.In various embodiments, each processor may be coupled to a memory or aplurality of processors may share a memory. The memory may include readonly memory (ROM), random access memory (RAM), static random accessmemory (SRAM), and dynamic random access memory (DRAM). In variousembodiments, power management subsystem 216 may be implemented as anintegrated circuit or using a field programmable gate array (FPGA), orcomplex programmable logic device (CPLD) for monitoring AP 204.

Referring now to FIG. 3A, there is provided a state diagram illustratingentry to and exit from mission critical standby for a portablecommunication device designed in accordance with some embodiments. Whilea particular order of states and transitions is indicated in FIG. 3A forillustrative purposes, the timing and ordering may vary whereappropriate without negating the purpose and advantages of the examplesset forth in detail throughout the remainder of this disclosure. Statediagram of portable communication device 300 may start at state 302. Invarious embodiments, portable communication device 300 may include anenergy source, such as a battery. In some embodiments, portablecommunication device 300 may include a battery that may be removable bythe user of portable communication device 300, such as battery 135 asdescribed for FIG. 1. When the battery is detached or dead at 320,portable communication device 300 may transition to unpowered devicestate 304. For example, a removable battery may be dead when the batteryis discharged beyond a minimum threshold necessary to power portablecommunication device 300. As another example, the removable battery maybe detached from portable communication device 300.

When a battery is attached or charged at 322, portable communicationdevice 300 may transition to power-on reset state 308. Portablecommunication device 300 may power up one or more power supplies inresponse to the battery being attached or charged at 322. For example,power supply 210 as described for FIG. 2 may power up one or more powersupplies, such as subsystem power supply 234. In some embodiments, thebattery may not be removable by the user of portable communicationdevice 300. The battery or portable communication device 300 may becharged beyond the minimum threshold necessary to power portablecommunication device 300. For example, battery 135 may be charged viaterminals 140 as described for FIG. 1. In some embodiments, the batterymay be removable from portable communication device 300. The removablebattery may be charged as described herein to provide power to portablecommunication device 300 or may be removed from portable communicationdevice 300 and replaced with another removable battery with a chargeabove the minimum threshold necessary to power. Skilled artisans willappreciate that in some embodiments other energy sources may be used topower portable communication device 300.

Portable communication device 300 may remain in power-on reset state 308while the power management subsystem is not initialized at 324. Thepower management subsystem, also referred to as the power state manager,may sequence the supply of power to the baseband processor (BP) and theapplication processor (AP). For example, power management subsystem 216as described for FIG. 2 may be initialized while portable communicationdevice 300 is in power-on reset state 308. Portable communication device300 may transition from power-on reset state 308 once the powermanagement subsystem has completed initialization.

Transition from power-on reset state 308 may be based on the state ofthe rotary control of portable communication device 300. When rotarycontrol is set to off at 330, portable communication device 300 maytransition to system-off state 306. In some embodiments, the rotarycontrol may be implemented as rotary control 212 as described for FIG.2. Although a rotary control is described, it will be appreciated thatin some embodiments other types of input devices may be used to indicatethe state of the radio associated with portable communication device300. When the rotary control is set to off at 330, the power managementsubsystem may set one or more status signals to indicate that the systemis powered off and may reset one or more timers corresponding to theapplication processor (AP). For example, power management subsystem 216as described for FIG. 2 may set main system status 230 to powered off,set application processor (AP) power enable 236 to powered off, setapplication processor (AP) status 238 to powered off, and reset theapplication processor (AP) standby timer.

When portable communication device 300 is in power-on reset state 308and the rotary control is set to on at 326, the power managementsubsystem may set one or more status signals to indicate that the systemis powered on and power communication device 300 may transition to coldsystem boot state 310. For example, power management subsystem 216 asdescribed for FIG. 2 may set main system status 230 to powered on and APpower enable 236 to powered on. A baseband processor (BP) of portablecommunication device 300 may be powered on when the rotary control isset to on and the power management subsystem may determine whether theBP is in a powered off state based on the setting of the rotary controland may set the status signals.

The BP may be able to process data associated with mission criticalcommunications within a few seconds of the rotary control being set toon. When portable communication device 300 transitions to cold systemboot state 310, the power management subsystem may sequence the supplyof power to the AP. For example, power management subsystem 216 asdescribed for FIG. 2 may indicate assert AP power enable 236 to powersupply 210, which may power on battery power supply 240 to supply powerto AP 204 via AP PMIC 208. To support mission critical communications,the BP may operate a real-time operating system (RTOS), which mayprocess communications without indeterminant delays. For example, theRTOS may enable the BP to receive or transmit communications within adefined period of time or within a defined amount of jittercorresponding to any delay of the communication being received ortransmitted. The AP of portable communication device 300 may be able toprocess data associated with communications many seconds after beingpowered on. The BP may power on and booting more quickly than the AP. Inat least some embodiments, the time required by the AP to power on andboot may be an order of magnitude longer than the time required by theBP.

An application processor power management timer (AP PM timer) may beused to delay the power up of the application processor (AP) until afterthe baseband processor (BP) has powered up. The AP PM timer may be tunedto isolate the surge in load associated with power up of the AP from thesurge in load associated with the power up of the BP. When anapplication processor power management timer (AP PM timer) is notexpired at 328, portable communication device 300 may remain in coldsystem boot state 310 and the power management subsystem of portablecommunication device 300 may set the AP status, such as AP status 238 asdescribed for FIG. 2, to indicate that the AP is powered off. In variousembodiments, the AP PM timer may expire after a defined period.Expiration of the AP PM timer may be determined using any suitabletechnique, including but not limited to, comparing a counter to athreshold to determine expiration of the AP PM timer based on whetherthe counter exceeds the threshold. When the AP PM timer expires at 338,the power management subsystem may start an application processor (AP)power-on timer, and portable communication device 300 may transition toapplication processor (AP) power-up state 312. When the AP power-ontimer has not expired at 348, portable communication device 300 mayremain in AP power-up state 312 and the power management subsystem maycontinue to set the AP status to indicate that the AP is powered offAlthough the AP is shown powering up after the BP powers up, the APpower up 312 may start before the BP startup is complete. In someembodiments the BP and AP may boot, reboot, or restart in parallel. Forexample, the BP and AP may be implemented as BP 202 and AP 204 asdescribed for FIG. 2, which may restart in parallel.

When the AP power-on timer expires at 346, portable communication device300 may transition to system-on state 314 and the power managementsubsystem may set the AP status to indicate that the AP is powered on.Portable communication device 300 may remain in system-on state 314while the rotary control is set to on at 350. When portablecommunication device 300 is in the system-on state 314 and the rotarycontrol is set to off at 354, portable communication device 300 maytransition to state 318 for standby operation for the power managementsubsystem and the power management subsystem may start a plurality oftimers. The plurality of timers may include an application processor(AP) standby timer, application processor (AP) cleanup timer, andapplication processor (AP) watchdog timer.

When portable communication device 300 is in the state 318 for standbyoperation for the power management subsystem and the rotary control isset to on at 358, portable communication device 300 may transition to APpower-up state 312. When portable communication device 300 is in state318 for standby operation for the power management subsystem and theapplication processor shutdown signal is asserted at 334, portablecommunication device 300 may transition to system-off state 306 and thepower management subsystem may set one or more status signals toindicate that the system is powered off and may reset one or more timerscorresponding to the application processor (AP). For example, powermanagement subsystem 216 as described for FIG. 2 may set main systemstatus 230 to powered off, set application processor (AP) power enable236 to powered off, set application processor (AP) status 238 to poweredoff, and reset the application processor (AP) standby timer. Whenportable communication device 300 is in state 318 for standby operationfor the power management subsystem and the application processor (AP)shutdown timer 342 expires, portable communication device 300 maytransition to AP PM off state 316.

When portable communication device 300 is in the system-on state 314 andthe AP status indicates that the AP is turned on or the basebandprocessor status (BP status) indicates that the BP is turned on at 352,the BP may operate to supervise operation of the AP. For example, BP 202as described for FIG. 2 may supervise AP 204 over input/output andbusses 250 and 254 through isolation buffer 214. In some embodiments,supervision by the BP may indicate that the AP is not operating asexpected. For example, supervision over input/output and busses 250 mayindicate that the AP is in a standby state or turned off when the AP isexpected to be turned on or that the AP is turned on when the AP isexpected to be in a standby state or turned off. As another example,supervision over input/output and busses 250 may indicate that the APlocked up or has failed to respond. When the AP is not operating asexpected, portable communication device 300 may transition to theapplication processor power management (AP PM) off state 316 and powermanagement subsystem may start an application processor (AP) powermanagement (PM) off timer and set a plurality of indicators. Theplurality of indicators may include setting the AP power enable toindicate that the AP is powered off, setting an application processor(AP) wake to indicate that the AP is in a non-active state and settingthe AP status to indicate that the AP is powered down. Portablecommunication device 300 may remain in AP PM off state 316 while the APPM Off timer has not expired at 356.

When portable communication device 300 is in the AP PM off state 316 andthe rotary control is set to off at 340, portable communication device300 may transition to system-off state 306. When portable communicationdevice 300 is in the AP PM off state 316 and a plurality of conditionsis satisfied at 344, portable communication device 300 may transition tocold system boot state 310, and the power management subsystem may setthe AP power enable to indicate that the AP is powered on and may startthe AP PM timer. The plurality of conditions may include the AP PM offtimer has expired, the rotary control is set to on, and the AP statusindicates that the AP is turned on. When portable communication device300 is in the system-off state 306 and the rotary control is set to offat 332, portable communication device 300 may remain in the system-offstate 306. When the rotary control is set to on at 336, portablecommunication device 300 may transition to cold system boot state 310.

Referring now to FIG. 3B, there is provided a state diagram illustratingmission critical standby for a portable communication device designed inaccordance with some embodiments. Although a particular order of statesand transitions is indicated in FIG. 3B for illustrative purposes, thetiming and ordering may vary where appropriate without negating thepurpose and advantages of the examples set forth in detail throughoutthe remainder of this disclosure. In FIG. 3B, the state 318 for standbyoperation for power management subsystem is shown as four states,including cleanup state 360, standby state 362, shutdown pulse state364, and shutdown state 366. Although four states are illustrated, state318 for standby operation for power management subsystem may include oneor more states in various embodiments. For example, in some embodimentsthe standby operation may include three states in which shutdown pulsestate 364 and shutdown state 366 may be combined to form a commonshutdown state that represents both the shutdown pulse and the shutdowntimer expiration. The power management subsystem, also referred to asthe power state manager, may sequence the supply of power to thebaseband processor (BP) and the application processor (AP) and maymonitor the AP when the BP is powered off to support mission criticalstandby. In some embodiments, the power management subsystem may permitcleanup operation on AP by supervising unexpected wakeup events by theAP and by returning the AP to standby or forcing the AP to shut down.

When portable communication device 300 is in the system-on state 314,the baseband processor (BP) may be powered on and may monitor theapplication processor (AP) to determine the power state of the AP. Insome embodiments, the power state of the BP may be controlled by arotary control of portable communication device 300. When the rotarycontrol is set to off at 354, the BP may power down, portablecommunication device 300 may transition to cleanup state 360, and thepower management subsystem may start a plurality of timers, includingbut not limited to, an application processor (AP) standby timer,application processor (AP) cleanup timer, and application processor (AP)watchdog timer.

Cleanup state 360 may provide the AP time to cleanup processingoperations before entering the standby. In some embodiments, the time tocleanup may be bounded by the power management subsystem to limit themaximum amount of time for cleanup operations. Cleanup operations by theAP may include one or more activities, including but not limited to,writes to clear flash memory coupled to the AP, application of asecurity patch, and processing of a long-term evolution (LTE) request.While the application processor (AP) watchdog timer has been tickled andthe application processor (AP) standby timer has not expired at 380,portable communication device 300 may remain in cleanup state 360 andthe power management subsystem may reset the AP watchdog timer. Forexample, the watchdog timer of AP 204 as described for FIG. 2 may betickled by power management subsystem 216 via AP tickle 246 when powermanagement subsystem 216 determines that AP 204 remains in an activestate. When the AP cleanup timer expires or the AP watchdog timerexpires at 382, portable communication device 300 may transition toshutdown pulse state 364, and power management subsystem may start anapplication processor (AP) power off timer. In some embodiments, thepower management subsystem may force the AP to shut down by setting theAP status to indicate the AP is powered off and setting the rotarystatus for the AP, such as rotary status 248 as described for FIG. 2, toindicate to the AP that the radio is switched on.

When portable communication device 300 is in cleanup state 360 and anapplication processor (AP) voltage signal, such as application processor(AP) power status 232 as described for FIG. 2, indicates that theapplication processor (AP) is in a non-operational low-power mode at372, portable communication device 300 may transition to standby state362 and the power management subsystem may stop the AP cleanup timer andthe AP watchdog timer. The AP may be inactive while the system is instandby state 362. For example, the AP may be in a standby state thatreduces the power consumed by the AP. Portable communication device 300may remain in standby state 362 while the application processor (AP)standby timer has not expired at 370. In some embodiments, the APstandby timer may be set by a user of portable communication device 300.The AP may wake from standby state 362 based on the operating platformexecuting on AP not being able to force the AP to remain in standby. Insome embodiments, the AP may fast wake from standby state 362 to processcleanup operations in cleanup state 360 before returning to standbystate 362.

When the AP voltage signal returns to operational mode at 374, portablecommunication device 300 may transition from standby state 362 tocleanup state 360 and the power management subsystem may resume the APcleanup timer and AP watchdog timer. The power management subsystem mayresume the AP cleanup timer and AP watchdog timer without resetting thetimers. When portable communication device 300 is in cleanup state 360or standby state 362, portable communication device 300 may transitionto application processor (AP) power-up state 312 when a plurality ofconditions is satisfied. The plurality of conditions may include theapplication processor (AP) standby timer not expiring, the applicationprocessor (AP) shutdown not being asserted, and the rotary control beingset to on at 368. When the plurality of conditions is satisfied, thepower management subsystem may set the AP status to indicate that the APhas turned off, may stop the AP standby timer, and may start the APpower-on timer.

When portable communication device 300 is in standby state 362, and therotary control is set to on and the AP standby timer expires at 376, theportable communication device may transition to shutdown pulse state 364and the power management subsystem may set the AP status to indicate theAP is powered off and may start the AP power off timer. While portablecommunication device 300 is in the shutdown pulse state 364, the powermanagement subsystem may provide a pulse to the AP to initiate shutdownof the AP. The portable communication device may transition to shutdownstate 366 after the shutdown pulse is provided. Skilled artisans willappreciate that the power management subsystem may provide a long pulseto the AP to force the shutdown of the AP. The portable communicationdevice may remain in shutdown state 366 while the application processor(AP) shutdown timer has not expired at 378.

When portable communication device 300 is in cleanup state 360, shutdownstate 366 or standby state 362, and application processor shutdown isasserted at 334, the portable communication device may transition tosystem-off state 306. The transition 334 to system-off state 306 mayinclude a hard shutdown to force the AP to shut down and power off.During transition 334, power management subsystem may set one or morestatus signals to indicate that the system is powered off and may resetone or more timers corresponding to the application processor (AP). Forexample, power management subsystem 216 as described for FIG. 2 may setmain system status 230 to powered off, set application processor (AP)power enable 236 to powered off, set application processor (AP) status238 to powered off, and reset the application processor (AP) standbytimer. Otherwise, when the AP shutdown timer expires at 342, portablecommunication device 300 may transition out of the standby operation forpower management subsystem to AP PM off state 316 and power managementsubsystem may set the AP power enable to indicate that the AP is notpowered on.

Referring now to FIG. 4A, there is provided a flow diagram of an examplemethod 400 for mission critical standby on a portable communicationdevice shown in accordance with some embodiments. While a particularorder of operations is indicated in FIG. 4A for illustrative purposes,the timing and ordering of such operations may vary where appropriatewithout negating the purpose and advantages of the examples set forth indetail throughout the remainder of this disclosure. In some embodiments,one or more portions of method 400 may be executed at some predeterminedperiodic time period thereafter, in response to a trigger raised locallyin the portable communication device. For example, the trigger may beraised in response to the need to support mission critical standby whenthe primary processor is shut down.

In this example embodiment, method 400 begins with block 405 in FIG. 4Aand continues to block 410, where a first command is received to shutdown the primary processor for a first operating platform. The firstcommand may correspond to input to change the state of the radiosupported by the primary processor. For example, the first command maycorrespond to the rotation of rotary control 212 as described in FIG. 2or the knob 110 as described in FIG. 1. In some embodiments, the firstcommand may be received by a power management subsystem, also referredto as a power state manager, which may sequence the supply of power tothe primary processor and a secondary processor of the portablecommunication device. For example, power management subsystem 216 asdescribed for FIG. 2 may receive the first command to shutdown BP 202from rotary control 212 via rotary control status 220. In someembodiments, power management subsystem may shutdown the primaryprocessor. For example, power management subsystem 216 as described forFIG. 2 may provide rotary status 224 to BP PMIC 206, which in responsemay power down BP 202 via BP power supply 227.

At block 415, a first timer may be started to limit time spent by asecondary processor of the portable communication device in standbymode. The first timer may be started in response to the receipt of thefirst command. For example, as described for transition 354 in FIGS. 3Aand 3B, the AP standby timer may be started when the portablecommunication device is in the system-on state 314 and the rotarycontrol is set to off. The secondary processor may be an applicationprocessor, such as AP 204 as described for FIG. 2. The secondaryprocessor may support low-power modes and may shut down when not active.The secondary processor may be monitored by the primary processor whenthe primary processor is powered on or by a power management subsystemwhen the primary processor is powered off.

At block 420, a second command may be sent to the secondary processor toinitiate cleanup operation on the secondary processor. The cleanupoperation may be completed prior to the shut down of secondary processorand may include any suitable operation appropriate for operation betweennormal active operation and a low-power state, including but not limitedto, writing to clear flash memory, applying a system updated, orresponding to a long-term evolution (LTE) request. For example, asdescribed for transition 354 in FIG. 3B, when the portable communicationdevice is in the system-on state 314 and the rotary control is set tooff, one or more timers may be started to initiate cleanup operation bysending a command, including but not limited to, the AP standby timer,AP cleanup timer, and AP watchdog timer. As another example, a commandmay be sent to initiate cleanup operation during transition 380 asdescribed for FIG. 3B such that the AP watchdog timer is tickled.

At block 425, method 400 may wait for the secondary processor completecleanup operation. At block 430, it may be determined whether the firsttimer expired relative to a first timeout value. In some embodiments,the first timeout value may be set by a user of the portablecommunication device. When the first timer expires, method 400 mayproceed to block 435. Otherwise, method 400 may return to block 425. Atblock 435, a third command may be sent to the secondary processor toshut down. The third command may be sent in response to a determinationthat the first timer expired. For example, a command may be sent to shutdown the AP during transition 376 as described for FIG. 3B. The commandmay set the AP status, such as AP status 238 as described for FIG. 2, toindicate that the AP is being shut down. As another example, the commandmay be sent to shut down the AP during transition 334 in FIG. 3B. Thecommand may set AP shutdown, such as AP shutdown 242 as described forFIG. 2, to force the AP to shut down. When the AP fails to respond tothe setting of AP shutdown, such as AP shutdown 242 as described forFIG. 2, and the AP does not enter a shutdown state, such as shutdownstate 366 as described or FIG. 3B, the power management subsystem mayforce the AP PMIC, such as AP PMIC 208 as described for FIG. 2, to turnoff the supply of power to the AP by re-asserting AP shutdown for anextended period of time.

Referring now to FIG. 4B, there is provided a flow diagram of examplemethod 440 for mission critical standby and cleanup operation on aportable communication device shown in accordance with some embodiments.While a particular order of operations is indicated in FIG. 4B forillustrative purposes, the timing and ordering of such operations mayvary where appropriate without negating the purpose and advantages ofthe examples set forth in detail throughout the remainder of thisdisclosure. In some embodiments, one or more portions of method 440 maybe executed at some predetermined periodic time period thereafter, inresponse to a trigger raised locally in the portable communicationdevice. For example, the trigger may be raised in response to the needto support mission critical standby when the primary processor is shutdown.

In this example embodiment, method 440 begins with block 405 in FIG. 4Aand continues to block 410, where a first command to shut down theprimary processor is received. At block 415, a timer to limit time spentby the secondary processor in a standby mode is started. At block 420, asecond command is sent to the secondary processor to initiate cleanupoperation. Blocks 410, 415, and 420 of method 440 may operate asdescribed for method 400 in FIG. 4A. At block 445, a voltage of thesecondary processor may be monitored. The voltage may be any voltagesupply to the secondary processor that is indicative of the activity onthe secondary processor. For example, the voltage of the secondaryprocessor, such as the secondary processor core voltage, may indicatewhether the secondary processor is in a standby state. The memoryassociated with the secondary processor may enter a self-refresh mode ofoperation, which may reduce the voltage of the memory to save power andmay maintain the data in the memory without sending or receiving datafrom the secondary processor. When the primary processor is powered on,the primary processor may monitor the voltage and when the primaryprocessor is powered off, a power management subsystem may monitor thevoltage. For example, power management subsystem 216 as described forFIG. 2 may monitor the voltage via application processor (AP) powerstatus 232. Based on the monitoring, an application processor (AP) maytransition between cleanup state 360 and standby state 362 as describedfor FIG. 3B.

At block 465, a watchdog timer of the secondary processor may bestarted. A watchdog timer may indicate whether the secondary processorhas locked up to reset or shutdown the secondary processor. In someembodiments, the watchdog timer may be used to limit the duration thatthe secondary processor remains in a cleanup mode. The watchdog timermay be tickled periodically when activity is detected on the secondaryprocessor. For example, power management subsystem 216 as described forFIG. 2 may tickle the watchdog timer via application processor tickle246. At 425, method 440 may wait for the secondary processor to cleanup,as described for method 400 in FIG. 4A. At 470, it may be determinedwhether the watchdog timer of the secondary processor expired. In someembodiments, the watchdog timer may expire when the countercorresponding to the watchdog timer reaches a value of zero after thecounter is reset to a specific value when the watchdog timer is tickled.Skilled artisans will appreciate that in some embodiments the counter ofthe watchdog timer may reset to a value of zero and increment such thatthe counter may exceed a threshold. When the watchdog timer expires,method 440 may proceed to block 475. At block 475, power to thesecondary processor may be removed in response to the expiration of thewatchdog timer. It may be determined that the secondary processor haslocked up or has failed to respond when the watchdog timer expires. Inresponse, method 400 may remove power to the secondary processor toreset or shutdown the secondary processor.

When the watchdog timer does not expire, method 440 may proceed to block430, where it may be determined whether a first timer to limit timespent by the secondary processor in standby mode expired relative to afirst timeout, as described for method 400 in FIG. 4A. When the firsttimer expires, method 440 may proceed to block 435, where a thirdcommand is sent to the secondary processor to shut down, as describedfor method 400 in FIG. 4A. At block 480, power to the secondaryprocessor may be shut down after a delay when the secondary processordoes not respond to the third command. For example, when AP 204 asdescribed for FIG. 2 does not respond, AP PMIC 208 may turn off thesupply of power to AP 204 by power management subsystem 216 re-assertingAP shutdown 242 for an extended period. After the extended period, AP204 may be forced to shut down when AP power supply 229 no longersupplies power to AP 204.

When the first timer does not expire, method 440 may proceed to block450, where it may be determined whether the monitored voltage is below athreshold. In some embodiments, the monitored voltage may be compared toa threshold associated with normal operation. Skilled artisans willappreciate that in some embodiments, the power supply of a portablecommunication device may perform the comparison and provide a statusindication to the power management subsystem. When the monitored voltageis below the threshold, method 440 may proceed to block 455. Otherwise,the method may return to block 445 to continue monitoring the voltage.At block 455, it is determined that the secondary processor enteredstandby based on the determination that the monitored voltage is belowthe threshold.

At block 460 it may be determined whether the secondary processor exitedstandby mode after initially entering standby mode. The determination ofwhether the secondary processor exited standby mode may be determinedbased on one or more indications of the state of the secondaryprocessor. The indications may include, but not limited to, monitoringthe state via the power management integrated circuit for the secondaryprocessor, monitoring the state of a clock generator for the secondaryprocessor, monitoring a timer or waiting on an interrupt correspondingto activity on the secondary processor, and monitoring a voltage of thesecondary processor that may increase above a threshold when thesecondary processor is active. When the secondary processor exitsstandby mode, method 440 may proceed to block 465. Otherwise the methodmay proceed to block 455.

In the foregoing specification, specific embodiments have beendescribed. However, one of ordinary skill in the art appreciates thatvarious modifications and changes may be made without departing from thescope of the invention as set forth in the claims below. Accordingly,the specification and figures are to be regarded in an illustrativerather than a restrictive sense, and all such modifications are intendedto be included within the scope of present teachings.

The benefits, advantages, solutions to problems, and any element(s) thatmay cause any benefit, advantage, or solution to occur or become morepronounced are not to be construed as a critical, required, or essentialfeatures or elements of any or all the claims. The invention is definedsolely by the appended claims including any amendments made during thependency of this application and all equivalents of those claims asissued.

Moreover in this document, relational terms such as first and second,top and bottom, and the like may be used solely to distinguish oneentity or action from another entity or action without necessarilyrequiring or implying any actual such relationship or order between suchentities or actions. The terms “comprises,” “comprising,” “has”,“having,” “includes”, “including,” “contains”, “containing” or any othervariation thereof, are intended to cover a non-exclusive inclusion, suchthat a process, method, article, or apparatus that comprises, has,includes, contains a list of elements does not include only thoseelements but may include other elements not expressly listed or inherentto such process, method, article, or apparatus. An element proceeded by“comprises . . . a”, “has . . . a”, “includes . . . a”, “contains . . .a” does not, without more constraints, preclude the existence ofadditional identical elements in the process, method, article, orapparatus that comprises, has, includes, contains the element. The terms“a” and “an” are defined as one or more unless explicitly statedotherwise herein. The terms “substantially”, “essentially”,“approximately”, “about” or any other version thereof, are defined asbeing close to as understood by one of ordinary skill in the art, and inone non-limiting embodiment the term is defined to be within 10%, inanother embodiment within 5%, in another embodiment within 1% and inanother embodiment within 0.5%. The term “coupled” as used herein isdefined as connected, although not necessarily directly and notnecessarily mechanically. A device or structure that is “configured” ina certain way is configured in at least that way, but may also beconfigured in ways that are not listed.

It will be appreciated that some embodiments may be comprised of one ormore generic or specialized processors (or “processing devices”) such asmicroprocessors, digital signal processors, customized processors andfield programmable gate arrays (FPGAs) and unique stored programinstructions (including both software and firmware) that control the oneor more processors to implement, in conjunction with certainnon-processor circuits, some, most, or all of the functions of thesystem, method, or apparatus described herein. Alternatively, some orall functions could be implemented by a state machine that has no storedprogram instructions, or in one or more application specific integratedcircuits (ASICs), in which each function or some combinations of certainof the functions are implemented as custom logic. Of course, acombination of the two approaches could be used.

Moreover, an embodiment can be implemented as a computer-readablestorage medium having computer readable code stored thereon forprogramming a computer (e.g., comprising a processor) to perform amethod as described and claimed herein. Examples of suchcomputer-readable storage mediums include, but are not limited to, ahard disk, a CD-ROM, an optical storage device, a magnetic storagedevice, a ROM (Read Only Memory), a PROM (Programmable Read OnlyMemory), an EPROM (Erasable Programmable Read Only Memory), an EEPROM(Electrically Erasable Programmable Read Only Memory) and a flashmemory. Further, it is expected that one of ordinary skill,notwithstanding possibly significant effort and many design choicesmotivated by, for example, available time, current technology, andeconomic considerations, when guided by the concepts and principlesdisclosed herein will be readily capable of generating such softwareinstructions and programs and integrated circuits (ICs) with minimalexperimentation.

The Abstract of the Disclosure is provided to allow the reader toquickly ascertain the nature of the technical disclosure. It issubmitted with the understanding that it will not be used to interpretor limit the scope or meaning of the claims. In addition, in theforegoing Detailed Description, it can be seen that various features aregrouped together in various embodiments for the purpose of streamliningthe disclosure. This method of disclosure is not to be interpreted asreflecting an intention that the claimed embodiments require morefeatures than are expressly recited in each claim. Rather, as thefollowing claims reflect, inventive subject matter lies in less than allfeatures of any single disclosed embodiment. Thus the following claimsare hereby incorporated into the Detailed Description, with each claimstanding on its own as a separately claimed subject matter.

We claim:
 1. A portable communication device, comprising a primaryprocessor for a first operating platform; a secondary processor for asecond operating platform, the secondary processor communicativelycoupled to the primary processor; and a power state manager, the powerstate manager configured to: determine whether the primary processor isin a powered off state; and sequence supply of power to the secondaryprocessor, the power state manager having: a first mode, the first modeto allow the primary processor to monitor a power state of the secondaryprocessor based on a determination that the primary processor is not inthe powered off state; and a second mode, the second mode to enable thepower state manager to monitor the power state of the secondaryprocessor based on a determination that the primary processor is in thepowered off state.
 2. The portable communication device of claim 1,wherein: the power state manager is in the second mode; and the powerstate manager is configured to sequence the power state of the secondaryprocessor between: a first state for cleanup operation of the secondaryprocessor; a second state for standby of the secondary processor,wherein state information of the secondary processor is maintained; anda third state for shutdown of the secondary processor.
 3. The portablecommunication device of claim 1, further comprising: a rotary knob toselect between the first mode and the second mode of the power statemanager.
 4. The portable communication device of claim 1, wherein theprimary processor and secondary processor are restarted in parallel whenthe power state manager enters the first mode.
 5. The portablecommunication device of claim 1, wherein the first operating platform isa real-time operating system for high-powered audio communications andthe second operating platform is a mobile operating system for broadbandapplications.
 6. The portable communication device of claim 1, furthercomprising: a battery configured to supply power to the primaryprocessor and the secondary processor.
 7. The portable communicationdevice of claim 2, wherein the power state manager is configured todetermine the power state of the secondary processor by monitoring avoltage of the secondary processor.
 8. The portable communication deviceof claim 2, wherein the power state manager is configured to: sequencefrom the second mode to the first mode by using a fast wake up of thesecondary processor.
 9. The portable communication device of claim 2,wherein the power state manager is configured to sequence the secondaryprocessor from the second state for the standby of the secondaryprocessor to the third state for shutdown of the secondary processor inresponse to expiration of a timer for suspended operation of thesecondary processor.
 10. The portable communication device of claim 5,wherein the high-powered audio communications include land mobile radiocommunications and the mobile operating system is Android.
 11. Theportable communication device of claim 7, wherein: the power statemanager determines the power state of the secondary processor is thefirst state based on the voltage of the secondary processor being abovea threshold; and the power state manager is configured to sequence thesecondary processor from the first state to the third state in responseto expiration of a watchdog timer, the watchdog timer being reset duringcleanup operation of the secondary processor.
 12. The portablecommunication device of claim 8, wherein the power state manager isconfigured to reset a standby timer for the secondary processorindependent of a configuration of the secondary processor to sequencebetween the second state for the standby of the secondary processor tothe first state for the cleanup operation of the secondary processor.13. A method for sequencing power of a portable communication devicehaving a primary processor for a first operating platform and secondaryprocessor for a second operating platform, the method comprising:receiving a first command in response to user input, the first commandto shut down the primary processor; in response to receiving the firstcommand, starting a first timer to limit time spent by the secondaryprocessor in a standby mode; sending a second command to the secondaryprocessor to initiate a cleanup operation, the cleanup operation to becompleted prior to shut down of the secondary processor; determiningwhether the first timer expired relative to a first timeout value; andsending a third command to the secondary processor to shut down based ona determination that the first timer expired.
 14. The method of claim13, further comprising: receiving a fourth command to power on theportable communication device; and initiating restart of the primaryprocessor and secondary processor in parallel based on the receipt ofthe fourth command.
 15. The method of claim 13, further comprising:starting a second timer to limit time spent by the secondary processorto shut down; determining whether the second timer expired relative to asecond timeout value; and removing power to the secondary processorbased on a determination that the second timer expired.
 16. The methodof claim 13, further comprising: determining whether the secondaryprocessor entered the standby mode by: monitoring a voltage of thesecondary processor; and determining whether the monitored voltage ofthe secondary processor is below a threshold, wherein the secondaryprocessor has entered the standby mode when the monitored voltage isbelow a threshold.
 17. The method of claim 13, wherein the user inputcorresponds to rotation of a knob on the portable communication device.18. The method of claim 13, further comprising: determining whether thesecondary processor exited the standby mode after the standby mode wasentered; starting a watchdog timer based on a determination that thesecondary processor exited the standby mode, the watchdog timer resetduring cleanup operation of the secondary processor; determining whetherthe watchdog timer expired; and removing power to the secondaryprocessor based on a determination that the watchdog timer expired. 19.The method of claim 13, further comprising: receiving a fourth commandin response to additional user input, the fourth command to power on theprimary processor; and stopping the first timer in response to thereceipt of the fourth command.
 20. The method of claim 13, furthercomprising: removing supply of power to the secondary processor when thesecondary processor completes shut down.
 21. The method of claim 13,wherein the cleanup operation to be completed by the secondary processorincludes handling a long-term evolution command, writing to flashmemory, or applying a security patch.
 22. The method of claim 13,wherein the first operating platform is a real-time operating system forhigh-powered audio communications and the second operating platform is amobile operating system for broadband applications.
 23. The method ofclaim 16, further comprising: stopping the first timer based on adetermination that the monitored voltage of the secondary processor isbelow a threshold.
 24. The method of claim 18, wherein determiningwhether the secondary processor exited the standby mode furthercomprises: monitoring a voltage of the secondary processor; anddetermining whether the monitored voltage of the secondary processor isabove a threshold, wherein the monitored voltage above the thresholdcorresponds to the determination that the secondary processor exited thestandby mode.
 25. The method of claim 22, wherein the high-powered audiocommunications include land mobile radio communications and the mobileoperating system is Android.